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I'm an engineer and Biology is my weakest point.

Lately I've been wondering, "Why do animals that have eyes tend to have exactly 2 of them?" The closest related answer I can find is that 2 eyes provide depth perception. However:

1. That answer really only answers why animals have more than 1 eye; it doesn't say why animals have 2 (as opposed to 3, or more); and
2. Depth perception can only explain animals near the top of the food chain - wolves, bears, humans - but not animals closer to the middle of the food chain - penguins, squirrels, or fish.

Predators typically have depth perception. Prey typically do not, even if they still have 2 eyes. I'm painting an entire kingdom in broad strokes, and obviously there are exceptions. Big sharks are pretty close to the top of the food chain, but they don't seem to have depth perception. (If they can turn their eyes 90 degrees forward they might get depth perception, but only over a narrow range. I mention this because I read a statement that animals with eyes on the sides of their heads have more depth perception, but I don't see how that can be true.)

This shortcoming of depth perception can be overcome if predators evolved vision first, and then some of their descendants evolved into predators while others evolved into prey.

So here's my question:

Did (near) apex predators evolve vision first? Or, is there any evidence to suggest that that's what happened?

I'm an engineer and biology is my weakest point, so please forgive if this question is dumb.

Lately I've been wondering, "Why do animals that have eyes tend to have exactly 2 of them?" The closest related answer I can find is that 2 eyes provide depth perception. However:

1. That answer really only answers why animals have more than 1 eye; it doesn't say why animals have 2 (as opposed to 3, or more); and
2. Depth perception can only explain animals near the top of the food chain - wolves, bears, humans - but not animals closer to the middle of the food chain - penguins, squirrels, or fish.

Predators typically have depth perception. Prey typically do not, even if they still have 2 eyes. I'm painting an entire kingdom in broad strokes, and obviously there are exceptions. Big sharks are pretty close to the top of the food chain, but they don't seem to have depth perception. (If they can turn their eyes 90 degrees forward they might get depth perception, but only over a narrow range. I mention this because I read a statement that animals with eyes on the sides of their heads have more depth perception, but I don't see how that can be true.)

This shortcoming of depth perception can be overcome if predators evolved vision first, and then some of their descendants evolved into predators while others evolved into prey.

So here's my question:

Did (near) apex predators evolve vision first? Or, is there any evidence to suggest that that's what happened?

I'm an engineer. Biology is my weakest point so please forgive if this question is dumb.

Lately I've been wondering, "Why do animals that have eyes tend to have exactly 2 of them?" The closest related answer I can find is that 2 eyes provide depth perception. However:

1. That answer really only answers why animals have more than 1 eye; it doesn't say why animals have 2 (as opposed to 3, or more); and
2. Depth perception can only explain animals near the top of the food chain - wolves, bears, humans - but not animals closer to the middle of the food chain - penguins, squirrels, or fish.

Predators typically have depth perception. Prey typically do not, even if they still have 2 eyes. I'm painting an entire kingdom in broad strokes, and obviously there are exceptions. Big sharks are pretty close to the top of the food chain, but they don't seem to have depth perception. (If they can turn their eyes 90 degrees forward they might get depth perception, but only over a narrow range. I mention this because I read a statement that animals with eyes on the sides of their heads have more depth perception, but I don't see how that can be true.)

This shortcoming of depth perception can be overcome if predators evolved vision first, and then some of their descendants evolved into predators while others evolved into prey.

So here's my question:

Did (near) apex predators evolve vision first? Or, is there any evidence to suggest that that's what happened?

I'm an engineer and Biology is my weakest point.

Lately I've been wondering, "Why do animals that have eyes tend to have exactly 2 of them?" The closest related answer I can find is that 2 eyes provide depth perception. However:

1. That answer really only answers why animals have more than 1 eye; it doesn't say why animals have 2 (as opposed to 3, or more); and
2. Depth perception can only explain animals near the top of the food chain - wolves, bears, humans - but not animals closer to the middle of the food chain - penguins, squirrels, or fish.

Predators typically have depth perception. Prey typically do not, even if they still have 2 eyes. I'm painting an entire kingdom in broad strokes, and obviously there are exceptions. Big sharks are pretty close to the top of the food chain, but they don't seem to have depth perception. (If they can turn their eyes 90 degrees forward they might get depth perception, but only over a narrow range. I mention this because I read a statement that animals with eyes on the sides of their heads have more depth perception, but I don't see how that can be true.)

This shortcoming of depth perception can be overcome if predators evolved vision first, and then some of their descendants evolved into predators while others evolved into prey.

So here's my question:

Did (near) apex predators evolve vision first? Or, is there any evidence to suggest that that's what happened?